Which BTU rating to use

dmg

My boiler has three ratings for the BTU (see below) Which one is used when sizing a boiler by a heat loss calulation?

AGA Input BTU = 50,000
D.O.E Heating Capacity BTU/HR = 42,000
IBR NEt Water Rating BTU/HR = 37,000

Paul Mitchell_2

Rating

Use net IBR this is the actual heat that will be provided to your home.

Constantin

Are you sure?

If all the piping/emitters./etc. are installed within the heating envelope, where is the heat going to go? My understanding of the IBR rating was that it would account for the heat loss of the pipes running through an unheated basement, exterior walls, etc. However, once the pipes are installed properly (i.e. within the heating envelope), the DoE rating should become much more relevant than the IBR rating, IMHO.

Weezbo

Your near boiler piping plays a large role.....

consider for a momment the amount of pipe off the near boiler....consider "different" developed lengths and sizes,think now what would THAT have to do with anything....it sounds implausable buh that is what is being refered to i belive that i could sucessfully put every btu in the boiler room and none in the rest of the house just by piping stradgeys and lots of pipes and fittings to match the available btus of a boiler.true it would get a bit warm in the room....thats OK. i could open a window.

hr

In the case

of the radiant heat jobs I do, often times the manifold for all the tube runs is right next to, or below, the boiler. Very little piping loss. This combined with sealed combustion boilers where there is no hole in the wall to let boiler jacket and piping heat outdoors ... I too feel DOE is the right number.

Maybe an old retro fit system with lots of iron poipe in cold walls or uninsulated through crawlspaces, etc, I'd use the lower number.

Guess it depends more on the actual installation and job conditions.

hot rod

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